1. Field of the Invention
The present invention relates to a power transmission device in which a transmission case includes a drive-side transmission case and a driven-side transmission case mounted onto the drive-side transmission case, and a method for assembling the power transmission device. The power transmission device and the associated assemble method have particular utility when employed with a motorcycle or a similar vehicle.
2. Description of the Related Art
Prior motorcycles have included transmissions with split transmission cases. Japanese Patent Publication No, 2000-130254 discloses an example of such a transmission. The disclosed transmission includes a drive shaft journaled by a drive-side transmission case such that one end of the drive shaft extends beyond the drive-side transmission case and is coupled with an internal combustion engine that generates power for traveling. A drive wheel is mounted onto the one end of the drive shaft. A driven-side transmission case is mounted onto the drive-side transmission case, and a driven wheel is journaled by the driven-side transmission case so as to be coupled with the drive wheel through a belt. The driven wheel is also drivingly coupled with a rear wheel of the motorcycle. A cover encloses the drive and driven wheels and the belt within the transmission cases.
Upon operation of the internal combustion engine, the power thereof is transmitted to the rear wheel through the drive shaft, the drive wheel, the driven wheel and the like, with the speed reduced. The driven rear wheel propels the motorcycle.
The above-described power transmission device is assembled in, for example, the following method. First, the drive-side transmission case is assembled. Specifically, for example, the drive shaft is assembled with the drive-side transmission case. Second, the drive wheel is temporarily placed onto the driven-side transmission case, and the endless member is wrapped around the drive wheel and the driven wheel. Third, the driven-side transmission case is mounted onto the drive-side transmission case, and the drive wheel is mounted onto the one end of the drive shaft. Finally, the cover member is mounted onto the driven-side transmission case to complete the assembly processes of the power transmission device.
As the conventional assembly methods has thus been described, the drive wheel is mounted onto the one end of the drive shaft as one of the last steps in the process; however, before this step, the drive wheel has been temporarily placed onto the driven-side transmission case. Because of this temporary setting, the drive wheel often unintentionally slips relative to or off from the driven-side transmission case. When this occurs, the assembly process becomes more complicated and difficult.